A conventional turbidimeter determines the concentration of solid particles suspended in a liquid sample by projecting a light beam through a cuvette comprising the liquid sample. A light detector detects the amount of light scattered by the suspended solid particulates in a right angle to the light beam axis. If the light detector detects light scattered in one single sector of the circumference, the signal of the light detector is relatively low.
US 2012/0170137 A1 describes different circular mirror and prism arrangements which coaxially surround the liquid sample cuvette to direct radially scattered light over the complete circumference to the light detector. These arrangements can lead to a significantly increased signal/noise ratio. These arrangements are, however, generally very sensitive to geometrical inaccuracies of the complete optical arrangement in addition to being very sensitive to local inhomogeneities of the turbidity of the liquid sample in the cuvette.